Changing Storage Controller Backend Managers

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Eucalyptus Versions:  3.3.0 and Greater

Changing Storage Controller Backend Managers

When cloud administrators initially set up Eucalyptus clouds for a small number of users, they will start out with using the Overlay backend [1] for the Storage Controller.  However, over time, as more users begin using the cloud, and begin to use EBS volumes in various ways (i.e. EBS-backed images, multiple EBS volumes attached to an instance, etc.), cloud administrators would like to migrate to a SAN backend for the Storage Controller.  This migration can be done in Eucalyptus, however there are a few caveats.

  • The caveats with regards to migrating Storage Controller backends are the following:
  • Any volumes that want to be migrated need to be backed up before migration to the new backend.
  • Data associated with the previous Storage Controller backend will be lost
  • Volumes must be detached from instances

Steps to Migrate Storage Controller Backends

Below is an example of changing Storage Controller backends.  The example shows the steps to move from the Overlay backend to the Dell Equallogic backend. The steps are as follows:

  1. Detach volumes from any running instance
  2. Back up volumes under /var/lib/eucalyptus/volumes directory on Storage Controller (SC)
  3. Deregister the Storage Controller (SC) - for example:
    • [root@odc-f-13 ~]# euca_conf --deregister-sc --partition acme --host 10.104.1.194 --component 194-storage-controller
  4. Confirm that SAN packages are installed on Cloud Controller (CLC) and Storage Controller (SC) machines respectively [2].
  5. If packages were installed after cloud had been running, restart the CLC and SC
    • service eucalyptus-cloud restart
  6. Once cloud services all show ENABLED state in the output from euca-describe-services, register Storage Controller (SC):
    • [root@odc-f-13 ~]# euca_conf --register-sc --partition acme --host 10.104.1.194 --component 194-storage-controller-equallogic
      SERVICE storage acme 194-storage-controller-equallogic LOADED 79 http://10.104.1.194:8773/services/Storage arn:euca:eucalyptus:acme:storage:194-storage-controller-equallogic/
      Registered the first storage controller in partition 'acme'. You must choose a storage back end with ``euca-modify-property -p acme.storage.blockstoragemanager=$BACKEND''
  7. After registering the Storage Controller (SC), set SAN backend:
    • [root@odc-f-13 ~]# euca-modify-property -p acme.storage.blockstoragemanager=equallogic
      PROPERTY acme.storage.blockstoragemanager equallogic was <unset>
  8. Set other cloud properties associated with the storage backend:
    • [root@odc-f-13 ~]# euca-modify-property -p acme.storage.sanhost=10.105.2.105
      PROPERTY acme.storage.sanhost 10.105.2.105 was <unset>
      [root@odc-f-13 ~]# euca-modify-property -p acme.storage.sanuser=grpadmin
      PROPERTY acme.storage.sanuser grpadmin was <unset>
      [root@odc-f-13 ~]# euca-modify-property -p acme.storage.sanpassword=pwd*4grpadmin
      PROPERTY acme.storage.sanpassword pwd*4grpadmin was ********

From there, the EC2 API service provided by Eucalyptus is ready for any EBS related requests.

References

[1]  Eucalyptus Installation Guide - Configuring the Storage Controller
[2]  Eucalyptus Installation Guide - Install Eucalyptus from Release Packages

 

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